The PPPL Perspective on Ten Year Planning

S. PragerPrinceton Plasma Physics Laboratory

Questions from panel to PPPL

(1) Describe initiatives over the next 5, 10, 15 years that wouldenhance PPPL's leadership in ensuring ITER-experiment success.

(2) Describe initiatives over the next 5, 10, 15 years that would inform the FNSF configuration decision (AT, ST, stellarator).

(3) If/when NSTX-U were to close, say in 5 years, 10 years, and 15 years, what would PPPL like to be involved in?

Focus this talk on magnetic fusion,discover science discussed elsewhere

Our process for selecting initiatives (in magnetic fusion)

10 year missionPrepare for a breakout to an energy development program

Strategic objectivesITER preparationSteady-state at high performancePlasma-material interfaceFusion nuclear materials

Selection criteriaImportance to success of fusionOpportunity for world leadership (realistically)Innovation

Select initiatives that satisfy the above

The same process can work for the panel

10 year missionPrepare for a breakout to energy development program

Strategic objectivesITER preparationSteady-state at high performancePlasma-material interfaceFusion nuclear materials

Selection criteriaImportance to success of fusionOpportunity for world leadershipInnovation

Select initiatives that satisfy the aboveIdentify activities to start up, activities to ramp down or, where

needed, additional review/advisory steps to decide

Will discuss assessment of PPPL,

in inverse order

No need for panel to define

Fusion Nuclear Science Facility

• The spherical tokamak offers a size advantage

• NSTX-U is essential to determine the physics feasibility of the ST FNSF (second to none in the world)

(see NSTX-U/ST white papers)

• QUASAR would provide key information for stellarator consideration as FNSF

• PPPL strives to play a lead role in FNSF design and research, independent of configuration

The plasma-material interface• Two approaches : solids (tungsten) and liquid metals

Neither is yet known to work in a reactor

• The world programStrong in tungstenOnly emerging work in liquid metals

• Liquid metals could be a breakthrough solutionLM should be studied co-equally with solids, worldwide

• Thus LM are a huge opportunity for US world leadership

• PPPL plans to have a comprehensive, collaborative program “atoms to tokamaks,” attack all the issues definitively

A possible game changer for a potential show stopper

• Stellarators are a mandatory research element to provide steady-state, disruption-absence, high gain

• Quasi-axisymmetric stellarators are a mandatory research element for size reduction (and physics understanding)

• Large gap in the world stellarator progam: only two large stellarators, and only one is “optimized”

• Therefore, PPPL envisions a future that includes forefront stellarator research

Steady-state, high performance plasmas

If we build a facility starting in ~ 5 years

• QUASAR is ideal – an affordable experiment that would be unambiguously at the world forefront, within a national program

Complex coils completed, toroidal sectors assembled

If we build a facility starting in ~ 5 years

• QUASAR is ideal – an affordable experiment that would be unambiguously at the world forefront

• Huge international supportJ. Li, ASIPP, China: “we would contribute components and staff… to reduce the U.S. costs for NCSX. Staff can include researchers, engineers, on-site assembly labor, etc.” [might reduce construction costs by ~ 30%]

Board of Scientific Directors, IPP, Germany: Quasar would, in our opinion, be the most innovative fusion experiment in the US since many years”

• A possible route to reduced-costs:

partnerships on construction ($105M ~ $80M, excl htng, diag)

can operate NSTX-U and QUASAR for 1.5 x the cost of either op alone

(shared infrastructure and staff; cost-effective opportunity)

(Operating cost increment ~ $30M/yr)

If a new US stellarator can only be built in 10 – 15 years

• Design a new stellarator (e.g., further turbulent transport, simplified coils, optimized divertor……)

• Partner internationally to build QUASAR outside the US (to make use of the NCSX hardware)

ITER preparation• The non-US tokamak facility base is impressive (JET, ASDEX-U, EAST, KSTAR, WEST, JT60-SA, FT-U…….) (ITER-like wall, DT, ITER shape, long pulse, high performance….) PPPL collaborates worldwide, and on DIII-D, C-MOD

• NSTX-U contributes substantially to ITERThrough unique ST features (e.g., robust energetic particle instabilities, EM

turbulence)Through areas where aspect ratio is not important(e.g., disruption mitigation, PMI studies)

• Integrated simulationThe US can lead (if we move rapidly)

What if the PPPL budget were flat for 10 years?

2015 20202025

NSTX-U NSTX-U (PMI)

QUASAR (3 yr const)

Major LM program

or

Prep studies for stellarator and LM programs

Prep studies major next steps in PMI, stellarator, FNSF

Liquid metal research

A More Sensible Plan

2015 20202025

NSTX-U NSTX-U (PMI)

QUASAR (3 yr const)

Major LM program

and

Prep studies for stellarator and LM programs

Prep studies major next steps in PMI, stellarator, FNSF

Liquid metal research

Summary

The US can contribute at the world forefront if we evolve the program over the next decade

Can be done in an orderly way, maintaining our core capabilities and human resources as facilities change

PPPL’s program is poised to perform at the world forefront for various US fusion futures